You may never have heard of them, but Massimo and Lella Vignelli are an almost daily influence in modern lives, especially if you live in New York. The logos for American Airlines, Bloomingdale's, Saks 5th Avenue and Ford, as well as 375 different national park brochures, many of the chairs we sit in and dinnerware we use, restaurants we visit and, most essentially, the subway map all spring from their feverishly creative minds as two of the foremost commercial designers of our time. Interiors, graphics, corporate brandings and products are their bailiwick, with their motto always being "If you can't find it, design it" and the instantly expressive Helvetica their preferred typeface.

Kathy Brew and Roberto Guerra's documentary Design Is One is a cheerful, inspiringly upbeat exploration of the duo’s dauntingly chic yet somehow warmly welcoming world, and the innumerable other worlds they have created. A charismatic, highly attractive elderly pair, they have been an "it" couple for decades, from the 1960s, when Massimo sported the very first Nehru jackets his intimates now agree he parted with only reluctantly. They are credited with first bringing real Italian style—devoid of tacky pizza associations—to this country in the 1960s. An impressive array of professional constituents like Richard Meier, Milton Glaser and Steven Heller weigh in with their somewhat awestruck, universally laudatory opinions of the couple. She is described as a bulldog by some observers for her strong personality and tenacity, while he is like a bounding puppy brimming with outrageous ideas, who has never taken a day off in his entire life, as his work is without a doubt also his fun.

Lella is celebrated here for her underappreciated architecturally trained strengths, while Massimo comes across as more the whimsical artist, whether with his concepts for chairs like "the handkerchief" (still proudly in production, as is so much of their output) or delivering a glass on deadline which was modeled after the dome of a cathedral he could see from his office. It was he, everyone agrees, who introduced the concept of the grid into modern design, something which continues to pervade everything he does.

The couple is famous for never arguing with a client—although the happy bickering between them over the course of their 50-year marriage and partnership is incessant. This, plus their undeniable talent, is what accounts for the supreme standing they have long enjoyed in their rabidly competitive field.

Computerization changed things drastically for the pair. Where once they presided over an exquisitely accoutered office that was, according to many, like “a chapel of design," they are now able to work out of the house with a drastically reduced staff. The cut-and-paste, hands-on approach is largely gone forever, but the glory of their work remains evident in what they are still producing today, as well as in timeless projects like Massimo's personal favorite, St. Peter's Church in Manhattan, fondly known as the "jazz church" for the performances and musician memorials given there, which is like an ingeniously assembled wooden puzzle of brilliant minimalism.